Lifting mechanism



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LIFTING MEcHANlsM; FiiedJan. 22, 1942 Patented Sept. `24, 11946 William L. Simonton, Dayton, Ohio, assigner to. ,y Y

The Joyce-Cridland Company, Dayton, Ohio, a n v corporation of Ohio Application January 2z, 1942, serial No. 427,717

9 Claims.

This invention relates to nf'ting lmeehamends,'

and more particularly to meansfor positively locking the lifting element in an v.elevated load supporting position. `In hydraulic lifts it has been customary heretofore to retain the lifting.

element, or ram, in an elevated position by closing the cutoff valve to prevent the escape of oil d or other iuid from the cylinder, andinthe event of the escape of fluid from the cylinder, due to a leaky valve or otherwise, the ram and the load thereon will move downwardly. Y ,Y

One object of the invention is to provide means for positively retaining the ramv in its elevated position. c

A further object of the inventionis to provide -a positiveV lock for the ram which willv automatically lock the same against downward movement immediately upon; a decrease inthe supporting pressure.

A further object of the invention is toprovide a locking device which Willbe in locking position at all times during the elevation of the rambut will permit the ram to move upwardly with relation thereto.` l

A further object of the invention is to provide such a locking device which may be moved to and retained in a position near the upper end ofthe ram to permit the latter to movedownwar'dly.

Otherobjects of the invention may appear as Y the mechanism is described in detail.

In the accompanying drawing Fig. iis a vertical section taken centrally through a lifting mechanism equipped with my invention, partly broken away, and showing the ram partly in ele-V vation; Fig. 2 is aV section taken on the line 2-2 of Fig. 1; Fig. 3 is a vertical section taken centrally through the locking device; and Fig. 4 is a detail view, partly in section, of another form of retaining device.

In the drawing I have illustrated one embodiment of my invention and have shown the same as applied to a hydraulic vehicle lift of a well known type which is designed primarily for use with airplanes, and when used for that purpose two orV more lifts, or jacks, are usually employed. It will be understood, however, that the invention may take various forms and may be utilized in connection with lifting mechanisms, orjaeks, of various kinds. e n

As here shown, the lifting mechanism com- 9 rigidly Ysecured thereto and has mounted within thesame abushing l to form a bearing for the ram. Asy here shown, this bushing is screw threaded into the upper end of the body 6, as shown at l l, and is provided with an annular pro- A jection or' flange-I2 which overhangs the upper edges'of the body portion 6 and the sleeve 9. The mainlifting element or ram I3 is mounted in vthe bearing [.0 for vertical movement within the cylinder. It is of a diameter somewhat less than the'int'ernal diameter of the cylinder and is provided at its lower vend with an enlargement I4 itting snugly within the body portion of the cylinderand constituting in eifect a piston head. The ram'in the Vpresent instance is tubular in forni and is closed at its lower end by a bottom wall l5. KAtits upper end the ram has mounted therein a bushing I6 having an internal thread to receive and adjustably support a supplemental] lifting element/Il'which is provided at its upper Y end-With awork engagingmember I8 and is held in adjusted positions by a locking nut I9.

The ram is provided in its external surface with e a spiral" groove 2U which preferably extends for substantially tneffull lengtn of the ram above the piston head IAand forms on the rama spiral rib, which, in the present instance, y is of a Width e greaterthan the width of the groove. The ram is heldv against rotation in the cylinder and for thispurpose is, in tne'present instance, provided with a vertical groove 2| which extends from the piston head |4'to the upper end of the ram. A spline'22 rigidly mounted .Within the upper end of thecylinder extends into the groove 2| and thus" preventsuthe rotation of the ram without`V interfering with its vertical movement. As here shown,A thespline is seated in a groove in the bearing bushing I0 and is rigidly secured therein by screws 23 extending through the sleeve 9, ,body portion jl!) and bushing, and thus serving to rigidly lock the bushing Aagainst rotation as well as to support the spline in the groove 2 l. Rotatably supported on the cylinder is a locking device 24 having a part extending into the spiral groove 20 of the ram and havingjsliding engagement with the lower wall` of that groove, so that as the ram moves upward'lythe locking device will be caused 1 by gravity to follow downwardly along the groove and to thus rotate about the ramV in contact with prises a cylinder 5 which consists of a tubular body portion 6 closed at its lower end by a capllke structure 'I rigidly secured thereto and pro-V v lded with a fluid inlet 8. At its upper` end .the body portion 6 is reinforced by an external sleeve or close to thecylinder. When fluid escapes from the cylinder or the Asupporting pressurek on the ram otherwise relieved the upper wall of the groove 20 will engage the locking device, in whatever position it may then occupy, and the ram will'be thus locked'against downward movement.

There are preferably two of f Thelower edge of each rib 25 is chamfered so that-it has free sliding contact with the lower wall of the groove 2i) as the ram is moved upwardly l-andthe" locking device will therefore follow-downfalongu the groove and will remain in contact with or close to the upper end of the cylinder. Whenthe ram tends to move downwardly the upper surface of the spiral groove will be brought into contact;l

with rib or ribs 25 and the .frictional contact between the .rib andthe wall of thegrooveand-be-'- .Y

tweentheannular Ymernber. and the-upper/end of y the .cylinder will prevent the rotation of thelocking. deviceand. it will therefore positively lock the ram .against downward movement. To in crease the ffrictional contact betweenthe locking device and the ram, the uppersurfaceof therib 25 of the locking .device is chamfered andthe upf ..1 perwall of thegroove20 is chamfeledas s hown,g

at 26.. Iheangularityof thechamfered.surfaces` beingsuchas to provide a relatively..great.i1`ic tional contactbetween the` same.

When the. ram is to be lowered the. locking. clevice ,24 is moved to a-positionnear. the .upper-.end

of the rain,` by manually rotatingthesame about theram, and is retained in that positionto perv mitthe rain to be lowered. Any suitable means maybe .provided for retaining thelocking device K in a position -nearthe uppeijendof theramand.

spaced from the. upper .end -of thecy1inder,.bi1t,z. as shown. in Figs. 1 to 3, a. diskll .is pivota11y..

mounted in a recess inthe :upperedgeof the ,an-

nularmemher. '.29 .onen ecentrcaxs by means..- of a. pivot nin 28,-s0 ,that the. dslsfcanrol'mellv be supportedoutlet Contact with the `.ramfrlut may, Y

be moved about. .its-axis .11.1110 thespral. groeve 29v to support the locking device on the ram in spaced relation to the cylinder. The disk, is of relatively thin-,flat construction andwhen inserted in the groove willso engage thewalls thereof as to prevent the vlocking device moving downwardly by.

gravity, Preferablyy a detent `is provided to re tain the 'eccentricallylmounted diskin the position to which it has been movedand, as herel shown, a'spring pressed ball .29 is mounted in a recessll'in the anular mem'ber 24 and the disk 21 ispr'ovided lwith. spaced recesses 3| to receive the detent and yieldabily resist the movement of the disk.

In Fig. 4 there is shown a modified formof device for retaining the follower. nut in its elevated position, this device comprising a set screw extending through the nutand adapted to engage the ram. As here shown,the set screw, 33, is

mounted in the nut 24a in an inclined position and the-inner end of the nut may be caused either'to enter the groove in the ram or to engage the outer surface of the spiral rib',

It will be apparent therefore that .when fluid is admitted to the lower end of the cylinder the ram will be forced upwardly but will beheld against rotation and the locking device; whichconstitutes a follower nut, will move downwardly along the spiral groove *andI remain in contact with or close to the upperend of the cyl-- inder; thus permitting the Aupward movement-of the ram and maintaining the projection or rib 25 always in a locking position with relation to the ram. When the ram has been elevated to the desired height the usual cutoff valve is closed to maintain a continuing support for the ram but should there be any leakage of fluid from the cylinderor shouldthe iiuid pressure be otherwise decreasedt'the tendency of the ram to move downwardly under its load will cause the upper wall of .the spiral groove to engage the rib of the locking device and will create such frictional contact between the upper wall of the groove and the rib and Abetweenthe locking device and the upperjendof the i cylinder as to prevent the rotation ,of .thejilocking device and thereby lock theram against downward movement, this locking Operation;.takingqeiect instantly upon the relief of the supporting pressure on the ram. When the ram is to be lowered and While it is supported by the uid within the cylinder the locking-device or follower nut is run` upward on the 1 yram to aposition spaced-fromthe upperend'of the'cylinder a distance sufficient to per-- mit the ram-to be lowered, and is retained -in that position by the retaining device 21 or 33. -1 v'Shouldthe'li-ftbe used, merelyas a jack,Y in an inclined or horizontal'pos/ition, in which the annular mem-l ber `or followerevnut -would not be retained by Y' gravity in ya position close to the cylinder," the nutfmayof course be moved to locking position with relation to the cylinder-in any suitable man-A ner, as by hand.

While I have shown and-described one em-- bodiment of my invention I wish it to be understood -that I do not'desire to be limited to the'- details thereofas various-'modifications may occur toa'person skilled' in the art.y

Having now fully'described ymy invention, what I claim as new and desire to secure by Letters Patent is:` Y

-1. A mechanism' comprisingy an upright tubular element, angelongateY yelement mounted for verticalmovement-in and `projecting beyond the upper end of said tubular velement and having an exterior spiralv groove, and a locking memberv extending about the projecting'portion of said elongategelement and vhaving va partextending into saidspiral groove to cause said locking member to rotate aboutsad elongate element under the influence of gravity as said elongate element moves Aupwardlytwithrelation-to said tubular element-and to be pressedV into locking relation to said tubular V'element by a downward force exe ertedv thereon by said elongate element.

2. A mechanismcomprising an vupright tubular elementfan elongateelement mounted. for. vertical movement-in and-projecting beyond :the

upperA end of said tubular element and having anexterior spiral groove, and an annular member rotatable-aboutthe projecting portion of said A elongatev element and normally held by gravita-y tionf'substan-tially contact-l with an vupwardly facng'surface of said'tubular element, saidannular 4member -having apart extendingr into said spiral '-groove; to slidably engage theV lower sur-H face thereof- A and cause said annular member to movedownward;

\- 3. InaY mechanismA com-prisingan-upright 'tubular Aelement and an elongate element; mounted for.k longitudinal movement in saidvtubular .element and heldl against rotation, said elongate element'having aspiral groove, an vannular member extending-"about said elongate element, supported Vnormally .by said tubular element land having aipart extending into said spiral groove, said part being adapted to engage the upper wall of said groove and to be pressed into rotation preventing engagement with said tubular element when said elongate element tends to move downwardly and tothus lock said elongate element against such downward movement, and to slide along the lower wall of said groove and rotate said annular element as said elongate element moves upwardly, said annular member tending to move by gravity toward said tubular element, said annular member being movable lengthwise of said elongate element to a positionl spaced from said tubular element to permit the downward movement of said elongate element, and a device carried by said annular member and movable into engagement with said elongate element to retain said annular member in said spaced position.

4. In a mechanism comprising an upright tubular element and an elongate element mounted for longitudinal movement in said tubular element and held against rotation, said elongate element having a spiral groove, an annular member extending about said elongate element, supported normally by said tubular element and having a part extending into said spiral groove, said part being adapted to engage the upper wall of said groove and to be pressed into rotation preventing engagement with said tubular element when said elongate element tends to move downwardly and to thus lock said elongate element against such downward movement, and yto slide along the lower wall of said groove and rotate' said annular member as said elongate element moves upwardly, said annular member tending to move by gravity toward said tubular element, said annular member being movable lengthwise vof said elongate element to a position spaced from said tubular element and a substantially at element mounted on said annular member in a plane intersecting said lelongate element and movable into said groove to retain said annularY member in said spaced position.

5. A lock for a mechanism of the type which includes an upright tubular element and an element mounted in said tubular element for longitudinal movement with relation thereto and projecting beyond the upper end thereof, said lock comprising a member supported normally by a xed part of said tubular element and rotatable about the projecting portion of said movable element, said rotatable member and said movable element having cooperating parts operable upon the upward movement of said movable element to cause said rotatable member to rotate under the influence of gravity in close proximity to said fixed part while said movable element moves upwardly with relation thereto, and to press said rotatable member `into rotation preventing engagement with said fixed part when said movable element tends to move downwardly, and thereby prevent said downward movement.

6. A mechanism comprising an upright tubular element, an elongate element mounted for longitudinal movement in and projecting beyondv one end of said tubular element and held against rotation therein, an annular member rotatably mounted about the projecting portion of said felongate'element and held by gravity substantially in contact with a xed part of said tubular element, said elongate element and said annular member having interengaging spiral parts to cause said annular member to rotate about said elongate element in close proximity to said fixed partof said tubular element as said elongate element moves upwardly and to be moved into rotation preventing engagement with said xed part when said elongate element tends to move downwardly.

7. In a jack device of the class described, in combination, a supporting member, a ram member associated therewith for raising and lowering movements vertically relative thereto, means for preventing rotation of said ram member relative to said supporting member while permitting said raising and lowering movements of said ram member relative to said supporting member, a lock member associated with said ram member for rotation relative thereto about a substantially vertical axis, said ram member and said lock member having parts including cooperating helical surfaces whose helix angle is such that, upon raising movement of said ram member relative to said supporting member, the weight of the lock member will cause rotational movement of said lock member downward by gravity relative to the ram member until the lock-member engages the supporting member, said lock member being cooperable with said supporting member to prevent rotation of said lock member relative to said supporting member upon such engagement,y

whereby to prevent unauthorized lowering movement of the ram member relative to the supporting member upon such engagement.

8. In a jack device of the class described, in combination, a supporting member, a rammemberassociated therewith for lifting and lowering movements relative thereto, a lock member associated with said ram member for rotation relative thereto about a substantially vertical axis, said ram member and said lock member having parts including cooperating helical surfaces whose helix angle is such that, upon lifting movement of said ram member relative to said supporting member, the weight of the lock member will cause rotational movement of said lock member downward by gravity relative to V the ram member until the look member engages the supporting member, said lock member being cooperable with said supporting member and said ram member to prevent unauthorized lowering movement of the ram member relative to the support upon such engagement, and'means on one of said lock or ram members movable into and out of engagement with the helical surfaces on the other member for preventing relative rotation of said lock and ram members when said means is so engaged, whereby to maintain Vsaid lock member in a xed position respecting said ram member, regardless of lifting or lowering movements of the ram, when said means is so-engaged.

9. In a, jack4 device of the class described, in combination, a supporting member, a ram member associated. therewith for lifting and lowering movements relative'thereto, a lock member associated with said ram member for rotation relative thereto about a substantially vertical axis, said ram member and said lock member having parts including cooperating helical surfaces whose helix angle is such that, upon lifting movement of said ram member relative to said supporting member, the weight of the lock 7 member WillA cause rotationalmovement of., said look member downwardby gravity relative to the ram member until the loekmembe'r engages the supporting member, said lockrmember being cooperable withv said supporting member and said ram member to prevent unauthorized lowering movement of the ram member relative to the supportxupon suchy engagement, and Yaneccent'ric member pivoted Onsaidlook member and movable into and out of. engagement with therhelical surfaces on the ram member. for preventing relative rotation of said nut and said ram member when said eccentric member is so engaged.

WILLIAM L; SIMONTON. 

